Alloys of manganese, chromium iron, and boron



Patented Now 12, 1940 I @NlTED STATES PATENT OFFICE ALLOYS F MANGANESE, CHROMIUM, moN,

- AND BOBON No Drawing. Application April 21, 1939, Serial No. 269,214

'1 Claims. (01. 75-126) My invention relates to manganese alloys and is particularly concerned with improvements in alloys consisting essentially of manganese, chromium and iron.

Ill the application of Reginald S. Dean, Serial No. 219,501, filed July 16, 1938, there are disclosed new anduseful alloys consisting essentially of chromium, manganese and iron, the manganese content ranging from approximately 25% to 20 approximately 66%, the chromium comprising up to about 17.5% and the balance being substantially iron. In the application of Reginald s. Dean, Serial No. 219,501, filed July 16, 1938, there are disclosed hardenable alloys consisting,

315 in the main, of manganese, chromium and iron wherein the manganese content ranges from about 20% to about 28%, the chromium content from about 14% to about 27%, and the balance being substantially iron.

20 My present invention relates to the further improvement of these alloys by the addition thereto of relatively small proportions of boron. The boron brings about various improvements among which may be mentioned a substantial re- 25 fining of grain and an increase in toughness of the alloys under consideration.

The boron may be introduced into the alloys in various ways. I have found it to be particularly satisfactory to efiect the introduction of the 3 boron into the alloys by heating said alloys at a temperature slightly above their melting points with an oxygenated boron compound such as borax, boric oxide, boric acid, or the like. In

this manner a small amount of boron is taken up w 35 by the alloy. It may also be added to the alloys in other ways such as by the addition. of elementary boron or by the addition of calcium .boride. I prefer, however, to employ boric oxide or borax because this brings about the removal of certain deleterious elements simultaneously with the addition of the boron to the alloys. The removal of sulphur from manganese alloys is more particularly claimed in my copending application, Serial No. 257,455, flied February 20, 1939, and I make no claim herein to the methods therein described.

The following examples are illustrative of the manner in which the novel alloys of my present invention may be produced. It will be under= stood, however, that said examples are given only by way of illustration and are not to be construed in any way as limiting the invention. Thus-for example, the composition of the particular manganese-chromium-iron alloys to which 55 the boron is to be added may be varied, the temperatures employed may be modified, and varying proportions of boron may be added to the alloys while still falling within the scope of my invention.

Example I 5 To 100 pounds'of an alloy containing about 37% manganese, 15.5% chromium, and the balance substantially iron, 5 pounds of borax were added and the mass was held at or just above the melting point of the alloy for about minw utes. The excess borax was then removed and the alloy was cast and hot worked down to a Hardness Temperature 35 uenched and quenched old Worked Re Re 40 Re 22 Re 43 Be 22 Re 50 Re 22 Re 58 80 Example II An alloy containing approximately manganese, 20% chromium and the balance substantially iron, was melted and mixed. with 10% by weight of borax, the mass being agitated and maintained slightly above the melting point of the alloy for a period of approximately 10 minutes. The excess barax was then removed and the alloy cast into suitable form. On analysis, the content of boron was shown to be 0.05%.

The resulting alloy was exceedingly fine grained, worked readily, and could be hardened by quenching from 1100 degrees C. followed by cold work and reheating to 700 degrees C. for 30 minutes whereupon it had a hardness of Re 58-60.

In order to. obtain the most satisfactory results, manganese of at least 99% purity should be employed. Particularly satisfactory results are obtained by utilizing electrolytic manganese. especially when preliminary desulphurized or desulphurized as an incident to the preparation of the alloys with which the present invention is concerned.

While the proportions of boron present in the alloy may be varied within some limits, it is preferred that the proportions do not substantially exceed 1% in order to obtain the most satisfactory results and preferably not substantially in excess of 0.3% based on the weight of the alloy as a whole.

What I claim as new and desire to protect by Letters Patent of the United States is:

1. Alloys containing up to about 24% chromium, from about 25% to about 66% manganese, from about 0.01% to about 1.0% boron, and the balance iron except for such small amounts of impurities as will not affect the properties of the alloys.

2. Alloys containing from about 12% to about 24% chromium, from about 25% to about 43% manganese, from about 0.01% to about 0.5% boron, and the balance iron except for such small amounts of impurities as will not affect the properties of the alloys, said alloys being hardenable by heating. quenching and aging treatments.

3. Hardenable alloys containing from about 11.5% to about 17.5% chromium, from about 25% to about 43% of electrolytic manganese ofat least 99% purity, from about 0.01% to about 1.0% boron, and the balance iron except for such small amounts of impurities as will not aifect the properties of the alloys.

4. Hardenable alloys containing from about 15% to about 16.5% chromium, from about 30% to about 37% manganese, from about 0.01% to about 0.5% boron, and the balance iron except for such small amounts of impurities as will not afiect the properties of the alloys.

5. Hardenable alloys containing from about 18% to about 24% chromium, from about 21% to about 34% manganese, from about 0.01% to about 1.0% boron, and the balance iron except for such small amounts of impurities as will not affect the properties of the alloys.

6. A hardenable alloy containing about 15% chromium, about 37% manganese; from about 0.01% to about 1.0% boron, and the balance iron except for such small amounts of impurities as will not affect the properties of the alloys.

'7. A hardened, heat treated alloy containing between 12% and 24% chromium, between 21% and 66% manganese, between 0.01% and 1.0% boron, and the balance iron except for such small amounts of impurities as will not affect the properties of the alloys;

c. TRAVIS ANDERSON. 

